The White House gave a full-throated and lengthy endorsement to decriminalizing cellphone and tablet PC unlocking on Monday, calling the matter “crucial for protecting consumer choice.”

The response — a reaction to the more than 114,000 signatures on a petition on the administration’s We The People site demanding legalization — also asserted that Americans ought to be allowed to use a device on any carrier in order to ensure “we continue to have the vibrant, competitive wireless market that delivers innovative products and solid service to meet consumers’ needs.”

“If you have paid for your mobile device, and aren’t bound by a service agreement or other obligation, you should be able to use it on another network,” wrote R. David Edelman, a senior adviser for Internet, innovation and privacy. “It’s common sense.”

The Librarian of Congress has ruled that cellphone unlocking is no longer exempted from the Digital Millennium Copyright Act. That means, as of Jan. 26, cellphone unlocking is a violation of copyright and punishable by law.

Some mobile-device owners wish to unlock their phones so they can use it overseas, switch carriers when a contract ends or use programs on it that the manufacturer may not have authorized.

The petition, created Jan. 24, was started by Sina Khanifar, a Silicon Valley technology activist. Khanifar is the founder of OpenSignal, which is building a worldwide database of cell towers, cellphone signal strength readings and Wi-Fi access points.

“This is a big victory for consumers, and I’m glad to have played a part in it,” Khanifar said in an emailed statement. “A lot of people reacted skeptically when I originally started the petition, with lots of comments to the effect of ‘petitions don’t do anything.’ The optimist in me is really glad to have proved them wrong. The White House just showed that they really do listen, and that they’re willing to take action.”

It’s not clear what action the White House can take — a change would most likely require an act of Congress — but Edelman signaled that the Department of Commerce’s National Telecommunications and Information Administration has written to protest this move.

In response to Edelman’s posting, the Library of Congress issued a news release saying it is willing to reconsider the decision.

“We also agree with the administration that the question of locked cellphones has implications for telecommunications policy and that it would benefit from review and resolution in that context,” the statement said.

“From a communications policy perspective, [criminalization] raises serious competition and innovation concerns, and for wireless consumers, it doesn’t pass the common-sense test,” Genachowski said. “The FCC is examining this issue, looking into whether the agency, wireless providers or others should take action to preserve consumers’ ability to unlock their mobile phones.”

Khanifar said the root of the problem is Section 1201 of the DMCA, what’s known as the anti-circumvention provision. He said White House officials told him Monday that they may mount a push to amend or remove it.